Optical metrology techniques are essential for process control of the gate formation process steps from lithography to the dielectric, spacers, gate and straining layer deposition in the sub-65nm technology nodes. Traditionally, optical metrology is based on the measurements of periodic lines or hole arrays using a spectroscopic ellipsometer or reflectometer, collecting data across a wavelength range at a single angle of incidence. In this paper, we discuss measurements using Focused Beam Ellipsometry (FBE), illuminating at discrete laser wavelengths while data is collected over a wide angle of incidence range. We verify precision estimates of the different model parameters with actual values obtained from measured data. We show sensitivity ranges for different applications over the space of measured wavelength spectrum from DUV to IR, angle of incidence range, and sample azimuthal orientations. Major factors contributing to the projected recipe performance - wavelength, orientation of the incident beam are discussed.

Date Published: 16 April 2008
PDF: 12 pages
Proc. SPIE 6922, Metrology, Inspection, and Process Control for Microlithography XXII, 69223O (16 April 2008); doi: 10.1117/12.772682

Published in SPIE Proceedings Vol. 6922:
Metrology, Inspection, and Process Control for Microlithography XXII
John A. Allgair; Christopher J. Raymond, Editor(s)